Fluid level indicating means for collapsible bag



Jan. 22, 1963 w, WHITNEY 3,074,451

FLUID LEVEL INDICATING MEANS FOR COLLAPSIBLE BAG Filed Sept. 2, 1960INVENTOR.

ATTORNEYS.

I anti or vaul- 3,074,451 FLUID LEVEL INDICATING F012 COLLAPSBLE BAGWilliam G. Whitney, Evanston, 113., assignor to American Hospr-nl SupplyCorporation, Evanston, iii, a corporation of illinois Filed Sept. 2,1960, Ser. No. 53,771 5 Claims. (Cl. 150-1) This invention relates to acollapsible bag, and more specifically, to a collapsible bag havingflexible walls and having means for indicating the level of the contentsdisposed therein.

The present invention is particularly suited for use in connection withthe administration of intravenous solutions. Collapsible plastic bagsare frequently used for this purpose because, among other things, thewalls of such bags fold together or collapse under external air pressureas the solution drains out, thereby eliminating the necessity andpossible dangers of introducing air into the container as it empties, apractice ordinarily required when bottles are used for this purposebecause of increasing air pressure resistanw to liquid flow as therigidwalled bottle is evacuated. However, because most intravenoussolutions are clear and because there is no clearly defined line ofdemarcation Where the Walls of a partially evacuated collapsiblecontainer meet, it is often quite difficult to detect the liquid levelwithin a transparent flexible bag. Thus, in administering a clearintravenous solution from a transparent plastic bag, a definite problemarises in readily determining the quantity of liquid remaining in the baIt is this problem to which the present invention is directed.

A principal object of the present invention is to provide a collapsibletransparent or semi-transparent bag equipped with indicating means whichenables a user to determine the amount of liquid removed from orremaining within the bag without observing the actual level of fluidwithin that bag. Specifically, it is an object to provide a collapsiblebag having markings on its transparent or semitransparent walls, themarkings changing in appearance as the liquid level within the containerdrops. Other objects will appear from the specification and drawings inwhich:

FIGURE 1 is a perspective view illustrating an embodiment of the presentinvention; FIG. 2 is an elevational view illustrating the collapsiblecontainer of FIG. 1 in fully emptied condition; 7

FIGURE 3 is a perspective view of a filled bag constituting a secondembodiment of the present invention;

FIGURE 4 is an elevational view of the bag illustrated in FIG. 3 inempty condition;

FIGURE 5 is a perspective view of a filled bag constituting a thirdembodiment of the present invention;

FIGURE 6 is an elevational view showing the bag of FIG. 5 in emptycondition.

In the embodiment of the invention illustrated in FIG- URES l and 2, thenumeral 1% generally designates a collapsible bag formed from flexibletransparent plastic material. The material should have low stretchcharacteristics and its flexibility should remain fairly constant overthe normal range of temperatures at which the bag is used. Polyethyleneand polyvinyl chloride plastic materials have been used effectively.

The term transparent as used herein refers to a plastic material havingsuiheient transparency so that when wo sheets of such material aredisposed in contiguous relation imprints or dark markings on the secondsheet may be seen through the first sheet. Therefore, while it ispreferable to form the bag from clear plastic material, it is to beunderstood that semi-transparent or translucent plastics which aretransparent within the meaning of the definition given above may also beused.

The upper end of bag it is flattened, sealed and folded upon itself toreceive a suitable supporting hook 11. At its lower end, the bag isprovided with a neck 12 which forms an outlet for the contents of thebag when the integral diaphragm or membrane provided thereby ispunctured by a needle. Thus, the bag in the illustration given isidentical to the intravenous solution bags in common use except forthose features which will be described shortly. If desired, the neck ofthe bag may be provided with a suitable stopper fixed therein ratherthan having an integrally-formed diaphragm, as is Well understood in theart.

The bag it? is provided with a pair of opposing and imperforate sideWalls 13 which are normally spaced apart by the fluid contents 14 or thebag but which are capable of flexing into contiguous relation as thecontents are withdrawn. When fully emptied, the bag assumes the flatrectangular shape illustrated in FIG. 2, the flattening of the sidewalls against each other being directed by the flattened and heat sealedportions at the upper and lower ends of the bag.

In FIG. 1, the bag is shown with its liquid contents partially withdrawnso as to illustrate more clearly the indicating means of the presentinvention. The indicating means essentially comprises a plurality ofshort horizontal lines 15 imprinted or otherwise applied to oppositeside walls 13 of the bag. The horizontal markings 15 are arranged inhorizontal groups at diiferent predetermined levels upon the bag and ateach level an appropriate numerical indicia 36 may be provided toindicate either the amount of liquid remaining in the bag or, as in theillustration given, the amount of liquid which has been withdrawntherefrom. The spaced markings on opposite sides of the bag arestaggered in complementary fashion. When the walls of the bag are spreadapart by the fiuid contents therein the markings appear as incomplete orbroken graduation lines but when the bag has been emptied (HG. 2) theside walls are disposed in contiguous relation so that the markings uponone wall are visible through the outer wall and bridge the spacingsbetween the markings of the latter.

From the foregoing, it is believed apparent that as liquid is withdrawnfrom the bag and the side walls of that bag flex into contiguousrelation the markings 15 which formerly appeared as a series of shorthorizontal lines assume the appearance of unbroken horizontal graduationlines. External air pressure forces the side walls of the evacuated orpartially evacuated container into tight surface contact so that themarkings upon one side wall simply appear as continuations of themarkings upon the opposite transparent side wall. The markings is arearranged at predetermined levels so that when the side walls are broughttogether and the markings at a given level appear as a continuousgraduation line an attendant or user may at a glance determine theapproximate amount of liquid which has been withdrawn from the bag. Forexample, FIG. 1 illustrates a bag from which at least cubic centimetersbut i-ess than 200 cubic centimeters have been withdrawn since the lineat the lOG level appears solid while the graduation line at the 280level appears broken or composed of a plurality of spaced short lines.It is important to note that such a determination of the amountwithdrawn from the bag (or the amount remaining therein) may be madequickly and easily without inspecting or attempting to ascertain theactual liquid level within the bag.

Proper registering of the markings as the bag is empties arises becauseof the construction of the bag along at least one of its edges. In theillustration given, the fiattened upper of th bag is largely responsiblefor guiding the side walls into proper relative positions although theflattened lower end construction and the lines of eeting of the sidewalls along the vertical edges of the bag contribute to a certain'extentin this regard. Depending on the size of the bag and the thickness andflexibility of the material from which it is formed, one ormore edges ofthe bag must be constructed so as to define a fold or flattened marginbetween the side walls to insure proper registry of the markings uponevacuation of the bag.

The embodiment of the invention illustrated in FIG- URES 3 and 4 of thedrawings is identical to the structure already described except that thelevel indicating means comprises horizontal groups of curved markings l5rather than straight horizontal lines. On one side wall of the bag, andspaced semi-circular marks face upwardly while on the opposite side wallof the bag such marks face downwardly. These complementary marks combineto define the composite graduation lines shown in FIG. 4 when thesidewalls of the transparent bag move into contiguous relation uponpartial or complete removal of the bags contents.

The markings for determining liquid levcl'may also take other forms.Thus, in FIG. 5, the markings 15" constitute complementary portions ofnumerical indicia, the complementary portion being imprinted orotherwise applied to opposite side walls of the bag. Until the sidewalls of the bag are brought together, these markings appear as randomand meaningless lines. However, when the bag is partially or fullycollapsed, the complementary portions of the numerical indicia appear tomerge and form the completed numerals illustrated in FIG. 6. In thisembodiment, the markings not only join to indicate the level of the bagscontents but also serve a secondary purpose, such as being the numbersthat are the volume indicia for the bag.

In all forms of the invention shown in the drawings and described above,the complementary markings of the respective side walls of the bags arebrought into juxtaposion when those walls are in contiguous relation todefine distinctive composite markings viewed in part through the bagstransparent walls. Each bag is provided with in complete ordiscontinuous markings on one side wall which appear to merge withsimilarly incomplete but complementary markings on the opposite sidewall when the bag is partially or completely emptied and which permit auser or attendant to determine quickly and easily the approximate liquidlevel within the bag.

In the foregoing specification, I have disclosed the present inventionin connection with a bag for administering intravenous solutions. Forthat reason, the volume markings increase in magnitude from the upper tothe lower portions of the bag. By observing the lowest merged lines ornumbers, an attendant may easily determine the amount of liquid whichhas been removed from the bag. It is to be understood, of course, thatwhere the bag is used to collect rather than administer liquids, suchas, for example, an evacuated drainage bag for collecting body fluids,the volume indicia might increase in order in an upward direction. Also,in such a case, the bag might have an opening at the top rather than atthe bottom; that is, an inverted form of the bag already described.Whether the bag is used for collection or administration, however, itwould in any event be part of a closed system wherein air is neitherintroduced nor expelled therefrom.

While in the foregoing I have disclosed an embodiment of the presentinvention in considerable detail for purposes of illustration, it willbe understood by those skilled in the art that many of these details maybe varied without departing from the spirit and scope of the invention.

I claim:

1. In a collapsible air-evacuated bag formed of flexible transparentplastic material and equipped with indicating means for indicating thelevel of the contents thereof, said bag having a pair of opposing sidewalls capable of assuming a spaced-apart relation when said bag isfilled and of flexing into contiguous relation when the contents of thebag are withdrawn, said indicating means comprising complementarymarkings upon the respective side walls of said bag, said side wallsbeing flattened together along at least one edge of said bag for theguiding of said side walls into register with each other as the contentsof said bag are withdrawn and for thereby bringing said complementarymarkings into juxtaposition to define distinctive composite markingsvisible through the bags transparent walls. I

2. In a collapsible air-evacuated bag formed of flexible transparentplastic material and provided with indicating means for indicating thelevel of the contents thereof, said bag having a pair of opposing sidewalls and having an opening for the passage of fluid between theinterior and exterior of said bag, said walls being capable of assuminga spaced apart relation when said bag is filled and of flexing intocontiguous relation when the fluid contents thereof are withdrawn, saidside walls being flattened together along at least one edge of the bagfor the guiding of said side walls into register with each other as saidcontents are withdrawn, said indicating means comprising portions ofgraduation markings at predetermined levels along the surfaces .of saidside walls, said portions of said markings at the same levels along therespective side walls being complementary to each other and beingbrought into juxtaposition to define comple'te graduation markingsvisible through said side walls when said side walls flex intocontiguous relation and into register with each other upon thewithdrawal of the contents of said bag.

3. The structure of claim 2 in which said complementary portions of saidgraduation markings are 'horizontally spaced apart at predeterminedlevels upon each side wall.

4. In a collapsible bag formed of flexible and substantiallynon-stretchable transparent plastic material, said bag having flattenedupper and lower ends and having a pair of imperforate side wallsnormally spaced apart by the contents of said bag but being flexibleinto contacting register with each other as said contents are drainedtherefrom, said side Walls being provided with complementary groups ofmarkings at predetermined levels thereon, the markings of the respectiveside walls at each of said predetermined levels being brought intojuxtaposition to define distinctive composite markings visible throughthe transparent walls of the bag when said walls flex into contact uponthe withdrawal of the contents from said bag. 7

5. In a collapsible bag formed from flexible plastic material andprovided with indicating means for indicating the level of the contentsthereof, said bag having a pair of transparent opposing side Walls beingflexible into juxtaposition when said bag is empty and being capa- 'bleof spreading apart to support fluid contents within said bag, saidindicating means comprising complementary groups of markings atpredetermined levels upon said respective side walls, the markings ofthe respective side walls at each of said predetermined levels beingbrought into visible association with each other to define completegraduation markings visible through said transparent side walls whencorresponding portions of said side walls at each of said predeterminedlevels are in juxtaposition.

References Cited in the file of this patent UNITED STATES PATENTS2,328,569 McGaw Sept. 7, 1943

1. IN A COLLAPSIBLE AIR-EVACUATED BAG FORMED OF FLEXIBLE TRANSPARENTPLASTIC MATERIAL AND EQUIPPED WITH INDICATING MEANS FOR INDICATING THELEVEL OF THE CONTENTS THEREOF, SAID BAG HAVING A PAIR OF OPPOSING SIDEWALLS CAPABLE OF ASSUMING A SPACED-APART RELATION WHEN SAID BAG ISFILLED AND OF FLEXING INTO CONTIGUOUS RELATION WHEN THE CONTENTS OF THEBAG ARE WITHDRAWN, SAID INDICATING MEANS COMPRISING COMPLEMENTARYMARKINGS UPON THE RESPECTIVE SIDE WALLS OF SAID BAG, SAID SIDE WALLSBEING FLATTENED TOGETHER ALONG AT LEAST ONE EDGE OF SAID BAG FOR THEGUIDING OF SAID SIDE WALLS INTO REGISTER WITH EACH OTHER AS THE CONTENTSOF SAID BAG ARE WITHDRAWN AND FOR THEREBY BRINGING SAID COMPLEMENTARYMARKINGS INTO JUXTAPOSITION TO DEFINE DISTINCTIVE COMPOSITE MARKINGSVISIBLE THROUGH THE BAG''S TRANSPARENT WALLS.